Tomcat example source code file (BeanELResolver.java)

This example Tomcat source code file (BeanELResolver.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

bean, beanproperties, beanproperty, class, class, concurrentcache, elexception, elexception, javabean, method, method, nullpointerexception, object, object, propertydescriptor, propertynotfoundexception, reflection, threading, threads, util

The Tomcat BeanELResolver.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package javax.el;

import java.beans.BeanInfo;
import java.beans.FeatureDescriptor;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;

public class BeanELResolver extends ELResolver {

	private final boolean readOnly;

	private final ConcurrentCache<String, BeanProperties> cache = new ConcurrentCache(
			1000);

	public BeanELResolver() {
		this.readOnly = false;
	}

	public BeanELResolver(boolean readOnly) {
		this.readOnly = readOnly;
	}

	public Object getValue(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		if (context == null) {
			throw new NullPointerException();
		}
		if (base == null || property == null) {
			return null;
		}

		context.setPropertyResolved(true);
		Method m = this.property(context, base, property).read(context);
		try {
			return m.invoke(base, (Object[]) null);
		} catch (IllegalAccessException e) {
			throw new ELException(e);
		} catch (InvocationTargetException e) {
			throw new ELException(message(context, "propertyReadError",
					new Object[] { base.getClass().getName(),
							property.toString() }), e.getCause());
		} catch (Exception e) {
			throw new ELException(e);
		}
	}

	public Class<?> getType(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		if (context == null) {
			throw new NullPointerException();
		}
		if (base == null || property == null) {
			return null;
		}

		context.setPropertyResolved(true);
		return this.property(context, base, property).getPropertyType();
	}

	public void setValue(ELContext context, Object base, Object property,
			Object value) throws NullPointerException,
			PropertyNotFoundException, PropertyNotWritableException,
			ELException {
		if (context == null) {
			throw new NullPointerException();
		}
		if (base == null || property == null) {
			return;
		}

		context.setPropertyResolved(true);

		if (this.readOnly) {
			throw new PropertyNotWritableException(message(context,
					"resolverNotWriteable", new Object[] { base.getClass()
							.getName() }));
		}

		Method m = this.property(context, base, property).write(context);
		try {
			m.invoke(base, value);
		} catch (IllegalAccessException e) {
			throw new ELException(e);
		} catch (InvocationTargetException e) {
			throw new ELException(message(context, "propertyWriteError",
					new Object[] { base.getClass().getName(),
							property.toString() }), e.getCause());
		} catch (Exception e) {
			throw new ELException(e);
		}
	}

	public boolean isReadOnly(ELContext context, Object base, Object property)
			throws NullPointerException, PropertyNotFoundException, ELException {
		if (context == null) {
			throw new NullPointerException();
		}
		if (base == null || property == null) {
			return false;
		}

		context.setPropertyResolved(true);
		return this.readOnly
				|| this.property(context, base, property).isReadOnly();
	}

	public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
		if (context == null) {
			throw new NullPointerException();
		}

		if (base == null) {
			return null;
		}

		try {
			BeanInfo info = Introspector.getBeanInfo(base.getClass());
			PropertyDescriptor[] pds = info.getPropertyDescriptors();
			for (int i = 0; i < pds.length; i++) {
				pds[i].setValue(RESOLVABLE_AT_DESIGN_TIME, Boolean.TRUE);
				pds[i].setValue(TYPE, pds[i].getPropertyType());
			}
			return Arrays.asList((FeatureDescriptor[]) pds).iterator();
		} catch (IntrospectionException e) {
			//
		}

		return null;
	}

	public Class<?> getCommonPropertyType(ELContext context, Object base) {
		if (context == null) {
			throw new NullPointerException();
		}

		if (base != null) {
			return Object.class;
		}

		return null;
	}

	protected final static class BeanProperties {
		private final Map<String, BeanProperty> properties;

		private final Class<?> type;

		public BeanProperties(Class<?> type) throws ELException {
			this.type = type;
			this.properties = new HashMap<String, BeanProperty>();
			try {
				BeanInfo info = Introspector.getBeanInfo(this.type);
				PropertyDescriptor[] pds = info.getPropertyDescriptors();
				for (int i = 0; i < pds.length; i++) {
					this.properties.put(pds[i].getName(), new BeanProperty(
							type, pds[i]));
				}
			} catch (IntrospectionException ie) {
				throw new ELException(ie);
			}
		}

		private BeanProperty get(ELContext ctx, String name) {
			BeanProperty property = this.properties.get(name);
			if (property == null) {
				throw new PropertyNotFoundException(message(ctx,
						"propertyNotFound",
						new Object[] { type.getName(), name }));
			}
			return property;
		}

        public BeanProperty getBeanProperty(String name) {
            return get(null, name);
        }
        
        private Class<?> getType() {
            return type;
        }
	}

    protected final static class BeanProperty {
		private final Class type;

		private final Class owner;

		private final PropertyDescriptor descriptor;

		private Method read;

		private Method write;

		public BeanProperty(Class<?> owner, PropertyDescriptor descriptor) {
			this.owner = owner;
			this.descriptor = descriptor;
			this.type = descriptor.getPropertyType();
		}

		public Class getPropertyType() {
			return this.type;
		}

		public boolean isReadOnly() {
		    return this.write == null
		        && (null == (this.write = getMethod(this.owner, descriptor.getWriteMethod())));
		}

		public Method getWriteMethod() {
			return write(null);
		}

		public Method getReadMethod() {
			return this.read(null);
		}

		private Method write(ELContext ctx) {
			if (this.write == null) {
				this.write = getMethod(this.owner, descriptor.getWriteMethod());
				if (this.write == null) {
					throw new PropertyNotFoundException(message(ctx,
							"propertyNotWritable", new Object[] {
									type.getName(), descriptor.getName() }));
				}
			}
			return this.write;
		}

		private Method read(ELContext ctx) {
			if (this.read == null) {
				this.read = getMethod(this.owner, descriptor.getReadMethod());
				if (this.read == null) {
					throw new PropertyNotFoundException(message(ctx,
							"propertyNotReadable", new Object[] {
									type.getName(), descriptor.getName() }));
				}
			}
			return this.read;
		}
	}

	private final BeanProperty property(ELContext ctx, Object base,
			Object property) {
		Class<?> type = base.getClass();
		String prop = property.toString();

		BeanProperties props = this.cache.get(type.getName());
		if (props == null || type != props.getType()) {
			props = new BeanProperties(type);
			this.cache.put(type.getName(), props);
		}

		return props.get(ctx, prop);
	}

	private final static Method getMethod(Class type, Method m) {
		if (m == null || Modifier.isPublic(type.getModifiers())) {
			return m;
		}
		Class[] inf = type.getInterfaces();
		Method mp = null;
		for (int i = 0; i < inf.length; i++) {
			try {
				mp = inf[i].getMethod(m.getName(), (Class[]) m.getParameterTypes());
				mp = getMethod(mp.getDeclaringClass(), mp);
				if (mp != null) {
					return mp;
				}
			} catch (NoSuchMethodException e) {
			}
		}
		Class sup = type.getSuperclass();
		if (sup != null) {
			try {
				mp = sup.getMethod(m.getName(), (Class[]) m.getParameterTypes());
				mp = getMethod(mp.getDeclaringClass(), mp);
				if (mp != null) {
					return mp;
				}
			} catch (NoSuchMethodException e) {
			}
		}
		return null;
	}
	
	private final static class ConcurrentCache<K,V> {

		private final int size;
		private final Map<K,V> eden;
		private final Map<K,V> longterm;
		
		public ConcurrentCache(int size) {
			this.size = size;
			this.eden = new ConcurrentHashMap<K,V>(size);
			this.longterm = new WeakHashMap<K,V>(size);
		}
		
		public V get(K key) {
			V value = this.eden.get(key);
			if (value == null) {
				value = this.longterm.get(key);
				if (value != null) {
					this.eden.put(key, value);
				}
			}
			return value;
		}
		
		public void put(K key, V value) {
			if (this.eden.size() >= this.size) {
				this.longterm.putAll(this.eden);
				this.eden.clear();
			}
			this.eden.put(key, value);
		}

	}
}